Solution properties of poly( N -methylethylene imine), a highly hydrophilic polycation

Poly(N-methylethylene imine) (PMEI) has a wide solubility similar to poly(ethylene oxide) and a high protonation capacity similar to poly(ethylene imine). In addition, PMEI forms aggregates with negatively charged macromolecules, such as polystyrene latex particles, and acts as either a flocculant or a dispersant depending on the environment. An aqueous solution containing the as-synthesized PMEI (weight-average molecular weight: 26 kDa) exhibited an LCST of 116 °C, and a toluene solution exhibited a UCST of 36 °C. Therefore, PMEI is expected to be used as a highly hydrophilic polycation for various applications.